The present invention relates to chemical mechanical planarization/planarization (“CMP”) polishing formulations (CMP composition or CMP formulations, CMP slurry or slurries are used interchangeably) for the CMP of patterned substrate surfaces, such as, for example, patterned semiconductor wafers.
More particularly, also described herein is a CMP polishing composition for polishing patterned wafers having multi-type films, such as barrier, Low k or ultra Low k, dielectric, and metal lines or vias or trenches.
There are several CMP steps in integrated circuit (IC) manufacturing process. When a CMP processing is applied, a multi-step CMP process may be employed involving the initial removal and planarization of the copper overburden, referred to as a step 1 copper CMP process, followed by a barrier layer CMP process. The barrier layer CMP process is frequently referred to as a barrier or step 2 CMP process.
CMP processing employed a barrier CMP composition at stage 2 is often used to remove and planarize excess metal layers and other films on the surface of the patterned wafers to achieve global planarization.
To address the issue of significant dielectric and metal, such as copper loss of the patterned wafer structure, a CMP stop layer can be used. The CMP stop layer can stop the metal CMP, especially barrier layer CMP, from removing dielectric layer underneath the barrier layer. The CMP stop layer is effective in protecting the structure against over-polishing. The CMP stop layer may be made of silicon containing materials, such as silicon nitride (abbreviated SiN), silicon oxide (SiO2), or silicon carbide (SiC). Thus, some CMP applications require very low removal rates for SiN and/or SiC, since they might be used a stop layer in a certain film stack.
There are works been done in the art to achieve very low SiN rates for shallow trench isolation (STI) applications. Babu et al. (Journal of The Electrochemical Society, 156, 12, H936-H943, 2009) or Carter et al. (U.S. Pat. No. 7,071,105; Electrochemical and Solid-State Letters, 8, 8, G218-G221, 2005) reported on additives to increase the selectivity of silicon oxide to silicon nitride.
Mainly, the addition of certain organic acids was used in the CMP slurries, as for example picolinic acid. However, all these prior art examples use ceria particles as abrasive which features a completely different removal mechanism than silica particles as abrasive so that additives which work with ceria like picolinic acid do not work at all with silica particles.
Furthermore, STI slurries are usually used at a pH range of 4-7 which is not suitable for advanced barrier applications due to potential corrosion issues on metal films.
Additionally, ceria slurries cannot be used in combination with hydrogen peroxide or other suitable oxidizer which are generally required to achieve sufficient metal or barrier film removal rates.
Therefore, there are significant needs for CMP slurries, methods, and systems that can perform CMP for very low removal rate on the stop layer (such as silicon containing layers) while providing other meeting other requirements such as removal rates for other layers, low dishing and low defects.